In continuous chromatography, several identical columns are connected in an arrangement that allows columns to be operated in series and/or in parallel, depending on the method requirements. Thus, all columns can be run in principle simultaneously, but slightly shifted in method steps. The procedure can be repeated, so that each column is loaded, eluted, and regenerated several times in the process. Compared to ‘conventional’ chromatography, wherein a single chromatography cycle is based on several consecutive steps, such as loading, wash, elution and regeneration, in continuous chromatography based on multiple identical columns all these steps occur simultaneously but on different columns each. Continuous chromatography operation results in a better utilization of chromatography resin, reduced processing time and reduced buffer requirements, all of which benefits process economy. Continuous chromatography is sometimes denoted simulated moving bed (SMB) chromatography or periodic counter current.
U.S. Pat. No. 6,325,940 (Daicel) relates to a simulated moving bed chromatographic system comprising packed beds filled with separating fillers, by which the separation performance of the packed beds can be evaluated without removing the packed beds from the circular fluid passage. As the packed beds can be evaluated without removal thereof, the system can be examined on whether the deterioration of the system is caused by the columns or not, and, if yes, which column causes the deterioration. The system comprises at least four packed beds connected in series and endlessly to each other and ports for adding and taking out fluid.
When connecting a number of chromatography columns in a simulated moving bed system there is a need for many valves and many tubes connecting the outlet of each column to the inlets of each of the other columns. In FIG. 1 a prior art simulated moving bed system 1 provided by GE Healthcare is shown. Four columns 3a,3b,3c,3d are connected in this simulated moving bed system. The outlets of each of the chromatography columns 3a,b,c,d can be connected to the inlets of each of the other columns in the system. These column connections are given number 5 in FIG. 1 and are provided through inlet and outlet valves which are provided to the inlets and outlets of each column. The Inlet and outlet valves comprise ports and control capabilities such that the correct valve ports are open at the right time, i.e. such that the flow into and out from the columns are directed correctly according to a simulated moving bed process. There is a need for an improved simulated moving bed system with regard to the numerous and complicated valves and tubes provided in the system.